Alkali-Silica Reactivity Interlaboratory Testing

Eleven laboratories participated in an inter-laboratory study to determine the precision of AASHTO T 303, The Test Method for Accelerated Detection of Potentially Deleterious Expansion of Mortar Bars due to Alkali Silica Reaction. Material variables included aggregate source and type, mineral and chemical admixture and test solution.

Statistical values were calculated before and after outlier data was removed. The multi-laboratory variability indicates a significant decreases with expansion above 0.01 percent. Above the expansion level of 0.10 percent, the single operator coefficient of variation was 4.1 percent and the multi-laboratory coefficient of variation was 16.9 percent when using the k and h statistic to determine outliers. A ruggedness test is recommended to reduce the sources of variation in the test procedure.

The Highway Operations Division is currently compiling information on smoothness specifications from a state survey. Information from this survey will be posted on this web site at a later date.